In active depth sensing, such as used by active rangefinders or active stereo systems, a projector projects patterns of light such as dots or lines to illuminate a region being sensed. The projected patterns are then captured by a camera/sensor (two or more in stereo systems), with the image (or images) processed to compute a depth map or the like.
For example, in stereo systems, stereo cameras capture two images from different viewpoints. Then, for example, one way to perform depth estimation with a stereo pair of images is to find correspondences between the images, e.g., to correlate each projected and sensed dot in one image with a counterpart dot in the other image via patch matching. For example, a dense depth map at the original (native) camera resolution may be obtained by area matching (e.g., a window of size 5×5). Once matched, the projected patterns within the images may be correlated with one another, and disparities between one or more features of the correlated dots (e.g., including their intensities) used to estimate a depth to that particular dot pair.
However, the resolution of the depth map is limited by the camera resolution.